Standard tangent-galvanometer



4 Sheetsi hest 1.

( NoMpdeL) E. WESTON. STANDARD TANGENT GALVANOMETER.

" Patented Apr. 9. 1889.

WITNESSES 7&4 ATTORNEY,

(No Model.) 4 Sheets-Sheet 2.

E. WESTON. STANDARD TANGENT GALVANOMETER.

Nd.400,980 PatexitedApnQ, 1889 WIT/V5885; v INVEIV TOR, I Ema/mum W BY ML ATTORNEY,

(No Model.) 4 Sheets-'Sheet 4.

E. WESTON. 7 STANDARD TA'NGENT GALVANOMETBR.

110.400.9220. Pa.tentedApr.'9,.1-889..

INVENTOI? lT/VESSES: Q i I 23% (AA/mm ATTORNEY UNITED STATES PATENT. OFFIo EDWARD WESTON, OE NEWARK, NE JERSEY.

. STANDARD TANGENT-GALVANOMETER.

- SPECIFICATION forming part of Letters Patent No. 400,980, dated April 9, 1889.

Applioation filed May 3, 1883. Serial No. 272,634. (No model.) I

To all whmn it may concern.-

Be it known that I, EDWARD WEs'roN, of

Newark, Essex county, New Jersey, have in-' vented a .new and. useful. Improvement in.

,line with the coil-centers and equidistant therefroms The needle is suspended from a "mirror, which in turn is supported by a'fiber, the rod joining mirror and needle being rigid,

so that the vibrations of the needleare trans- Thebase of thecentral standard in my pres -mitted to the mirror. pmred upon a tripod-base, which is provided- The standard is supwith'the usual leveling-screws.

entapparatus rests upon a larger base or o' 3 the center of which the standard column "passes. The index-mirroris arranged in that "platform, which is also provided with suitable leveling screws. Supported from said lastmentioned base is a circular chamber, through part of the column which is wholly inclosed bottom walls of the chamber. I

' by said chamber. Upon the inner periphery iflections of the mirror, and in the Wain Ofthe of the chamber is a scale for showing th'edechamber-maybe disposed:sight openings or telescopes directed toward the mirror, so'that by looking .into said telescopes the scale on the inner periphery of. the chambermay be seen reflected in, the mirror. At the point "Wh'erethe standard column passes through thescale -'chamber a universal joint 15 proin'ded, which allows ofa suitable amountof play between the standard and the top and My invention r'consists' in the combination of the index-mirror aud t-he circular scale extending around the same, in the marking of said scale', in' the combinatlon of "the m rror with a scalemarkediasifdescribed andwith telescope in lieu of two.

.diflt'e'ren'tial conductors upon a coil.

sight-openings arranged as set forth, in the construction. and arrangement of the scale chamber and its combination with the galvanometer standard, and in the novel construction of the coils of the instrument, together with various other novel instrumentalities and combinations, all as hereinafter more particularly set forth. a

The object of my invention is to providea standard tangent-galvan ometer provided with a suitable scale for showing themirror deflections, the said scale being arranged so that a very wide range of measurement can be had and the instrument and scale forming one apparatus.

--In the accompanying drawings, Figure 1 is a plan view of my galvanometer. Fig. 2 is an elevation thereof- Fig. 3 is a diagram show ing the arrangement of scale, two telescopes, "and mirror.

Fig. 4 is adiagram showing the arrangement of scale and mirror with one Fig. 5 is a diagram showing the arrangement of scale and mirror with a lamp in, place of the single telescope shown in Fig. 4. Fig. 6 is a section of the s'calechamber and telescope on the line as as of Fig. 4. Fig. 7 is a section of the scalechamber and lamp on the line 2 z of Fig. 5. Fig. 8 is a fan view of the scale as repre- Sented in Fig. 3. 9 shows in detail the 'device for permitting some play of the central supporting-column at the points where it passes through the covering-plates of the scale-chamber. Fig. 10 is a section on the line 3/ y of Fig. 9. Fig. 11 is a plan view of the centering .device for the tripod. Fig. 12'

is a diagram illustrating the arrangement of is aside view "of a coil, and Fig. 14 a section thereof on the line wx' of Fig. 13'. Fig. 15 is an enlarged partial section of the coil, show- Fig. 13

ing the arrangement of conductors .in the side and periphery of the spool. Fig. 16, is 9. diagram showing the arrangement of the differential conductors with reference to the center of the magnet.

- Similar letters of reference parts.

A is a central hollow standard pivoted at indicate like i'tslo'wer extremity upon the tripod B. Upon I opposite sides of standard are fixed supports or brackets, to which are secured the spools R, upon which are wound the coils. These coils may either consist of a single conductor wound in the usual way continuously around the periphery of the spool or two conductors, p and q, wound separately, as set forth farther on in this specification. Upon the tripod B is a .horizontal worm-screw, N, which engages witha toothed segment upon the enlargement 0 on the lower partof the standard A. By turning the screw N the standard A may be rotated upon its vertical axis, and the coils thus adjusted in the magnetic meridian. In an enlargement at about the middle of the standard A is arranged a cylinder, E, of diamagnetic metal, having a central chamber in which is suspended a ring-magnet, F.

The cylinder-block E is made of diamagnetic metal, so as to dampen or check the oscillations of the magnet inclosed in the central chamber. Said block is divided transversely into halves, and the parts are inserted into the bore of the enlargement of the standard A from opposite sides,.and are connected together by screws.

Seated in a socket in the upper end of standard A is a glass tube, I, having at its upper extremity a vertically-adjustable hook or other support, to which is attached'a fiber of silk or other suitable material. This fiber carries the mirror H, which is situated in the chamber P in standard A. The side of this chamber is open, so thatthe face of the mirror is exposed. Depending from the mirror is a light aluminium rod, which at its lower end carries the magnet F. At the extremities of the arms of the tripod B are levelingscrews of usual construction. 0

The construction and relation of standard A and coils are such that a line joining the centers of the coils intersects the longitudinal axis of the standard at right angles thereto, and the magnet F is disposed so that its center coincides with this point of intersection. 4

The aforesaid instrument is placedupon a base, K, upon which is disposed a circular plate, M, upon the upper side of which are formed three grooves, g g g", radiating at angles of one hundred and twenty degrees. The lower ends of the supporting-screws of the tripod B rest in the said grooves, and as said ends are accurately equidistant from one another and from the center of the tripod it follows that when they are so placed the centers of the plate M and tripod B mustecoincide, and the tripod is thus self-centered upon the base K. From the base K rise three pillars, J, which support the scale-chamber O. This chamber consists of 'a peripherical ring, G,'which rests upon the pillars J, and is cov: ered above and below by glass plates f and 1), Figs. 6, 7, and 9.

The standard A passes through the scalechamber C, the upper and lower plates of which come above and below the chamber in said standard,'wherein the mirror H is suspended. In order to allow of movement of the standardA inthe opening of said plates through which itpasses, as is necessarywhen the instrument is raised or lowered or leveled by means of the screws in the arms of the tripod B, the hole h, Fig. 9, cut through the upper plate, f, is made larger than said column, and the annular opening thus left is covered by a loosely-fitting collar, 8, provided on its lower side with a soft-rubber washer, j. In

'vice permits the requisite movement of the central standard and efiectually prevents the access of dust or air-currents to the chamber (J.

Around theinner periphery of the inclos in -rin O of chamber 0 is marked a' scale,

andpassing through said ring are two telescopes, T -and T. The disposition of this scale. and its relation to the telescopes and the mirror H, I will now describe, reference being had more particularly to the diagram, Fig. .3.

Let H represent the position of the mirror at restthat is, when no current traverses the coils. The circle W represents the inner periphery of the ring 0, on which the scale is marked. From the point Z (a radial line from which point meets the face of the-mirror at right angles) is set ofl on each side an arc of forty-five degrees, and at the ends of these arcs the telescopes T T are located. Therefore these telescopes are ninety degrees apart, and lines drawn from each telescope to the mirror will make equal angles of fortyfive degrees with the line drawn from Z to mirror-face. Consequently an observer look .ing at the mirror through telescope T will see reflected therein the image of a zero-point of the scale marked at the telescope T, while on looking at the mirror through the telescope T he will see another zero-point which is marked at the telescope T. Now from the telescope T around to the point X is one hundred and eighty degrees, and equally .from the telescope T around to the point Y is one hundred'and eighty degree Suppose next that the mirror H be deflected over an angle of forty-five degrees to the position H, dotted lines. This is obviously at right angles to the line of sight of telescope T, and the forty five-degree mark at that telescope will be directly reflected back into it. If the mirror moves still further in the same direction, as to the position H. then the end of the scale at X will be seen in telescope T. Now the total movement of the mirror has been but ninety degrees, but the image of the scale has been reflected overan aircof one hundred and eighty degrees. This because of the wellknown optical law that the angular movement of the reflected ray is equal to twice that of eighty degrees of the scale as ninety degrees,

lamp, as shown in section in Fig. 5, and ob-- vation of the mirror.

Fig. 3, and hence the reflected image of the scale-reading shows the actual angle of devi- Consequently by observing the mirror through telescope T, when the direction of the current in the coils is such as to 'move the needle into thepositions indicated by the dotted lines H H", I can measure itsangular deviation of ninety degrees upon'an arc-of one hundred and eighty.

degrees from the zero-point at telescope T to the point X, and equally when the current is in the other direction, and by observing the mirror through the telescope T, I can measure its angular deviation over the corresponding scale-distance from the zero-point at telescope T to the point Y.

It will be apparent that by this construction I am enabled to augment the useful scale range of instruments of this class, and as one degree deflection of the mirror is represented by two degrees of the scale I am also enabled to note slight variations in deflection with accuracy. This device also affordsa very certain and easy mode of proving the correct adjustment of the needle. If'the mirror, when observed through telescope '1, reflects the zero at telescope T, and vice versa, then obviously its center point must be in the axial line'joining the centers of two coils. Then, in order to prove that the coils are in the magnetic meridian, in which case the deviation of the needle will be the same on either side of the zero-point, it is requisite to simply establish the current and note the .deflection through one telescope and then reverse the current and note the deflection through the other telescope. If the readings are the same in both telescopes, the'deflections are equal and the coils are in the magnetic meridian.

In Fig. 8 is shown a face view of the scalemarking.

While I greatly prefer the arrangement of the scale above described andof two telescopes, I may employa single telescope located' at the point Z, with its line of sight at right angles to the mirror H when at rest; but in "suchcase the scale is to be marked each way from a zero-point located at said point Z, as shown in Fig 4', (t-wo degrees, as before, being marked as one degree.) Instead of the telescope, I may here substitute a serve the position of the reflected beam on the scale in the usual manner.

- The coils, as already'stated, may comprise each a single conductor, or they may be made dilferential and each include two conductors, as p 'and q, wound upon the sa'me ring, B. As shown in Figs. 13, 14, and 15, a groove or channel is made in the periphery of the ring It to receive one conductor, and a second groove in the face or side of the ring to receive the other conductor. These grooves are so disposed that when the ring is in place a cone passing through the center of both wires will have its apex at the center of the magnetizedneedle, as indicated in the diagram, Fig. 16, the objectbeing to preserve the ratio between the diameter of the turns of the reductors p and q a current may be passed through them, respectively, in opposite or in thesame'direction. In the former case the deflection of the magnet will be due to the differential elfect thereon of thecurrent in the wires, and thus very large currents'may be measured with small deflections. Again, as the" instrument is arranged with two coils, one on each side, each of which may contain differential conductors, connections between said conductors may be made so as still further to reduce the effect of strong currents on the needle. In this way I avoid the necessity of using coils of very large diameter for the measurement of strong currents in instruments of this class.

The conductors leadirig from the coils are twisted together, and also carried outward in a line radial to the coil-center and in the horizontal plane of vibration of the needle, as

shqwn in Fig. 13, so as to prevent any extraneous inductive efiect which they might exercise upon the magnet. I

IIO

It will of course be obvious that the com- 4 bination and arrangement of index-mirror, scale, and scale-chamber herein set fort-h may be utilized in various electrical instruments designed for testing or measuring-such, for example, as electrometers-and it should be understood, therefore, that I'do not limit'my invention in this respect specifically to its combination in and with a galvanonieter.

1. In combihation with an electrical instrument containing a vibrating index-mirror, a

curved surface extending around said mirror and concentric with the axis of vibration thereof, and a scale upon said surface for showing the angular deflectionsof said mirror, substantially as described.

- 2. In combination with an electrical instrument containinga vibrating index-mirror, a curved surface extending around said mirror and concentric with the axis of vibration thereof, and a scale upon said surface for rent traverses the instrument, substantially as described.

3. In combination with an electrical instrument containing a vibrating index-mirror, a curved surface extending around said mirror and concentric with the axis of vibration thereof, and a scale upon said surface for showing the deflections of said mirror,- the said scale having two zero-points marked, respectively, at points on said surface distant forty-five degrees in are and at each side of the point at which a radius from the mirrorcent-er drawn perpendicular to the mirrorface meets said surface when no current traverses the instrument, substantially as described.

4. In combination with an electrical instrument containing a vibrating index-mirror, a curved surface extending around said mirror and concentric with the axis of vibration thereof, and a scale upon said surface for showing the deflections of said mirror, the

said scales having two zero-points marked,

respectively, at points on said surface distant forty-five degrees in arc and at each side of the point at which a radius from the mirrorcenter drawn perpendicular to the mirror-face meets said surface when no current traverses the instrument, and the said scale being laid off in regular successive divisions from each of said zero peints toward the other, substantially as described.

5. In combination with an electrical instrument containing a vibrating index-mirror, a wall extending around said mirror and having its inner periphery curved and concerntrie with the axis of vibration of said mirror, a scale on said periphery for showing the angular deflections of said mirror, and a sightopening in said wall in line wit said mirror, substantially as described.

6. In combination with an electrical instrument containing a vibrating index-mirror, a wall extending around said mirror andhaving its inner periphery concentric with the axis of vibration of said mirror, a scale on said periphery for showing the angular deflections of said mirror, and a sight-opening in said vwall in line with said mirror, the position of said opening in said wall being such that a line of sight drawn from said opening to said mirror shall inake an incident angle offortyfive degrees with the reflecting-surface when no current traverses the instrument, substantially as described.

7. In combination with an electrical instru- "ment containing a vibrating index-mirror, a

wall extending around said mirror and having its inner periphery concentric with the axis of vibration'of said mirror, a scale on said periphery for showing the angular deflections of said mirror, and two sight-openings in said nular spool or traverses the instrument, substantially as described.

8. In an electrical instrument, a vibrati index-mirror and a scale-chamber said mirror, substantially as described.

9. The combination of an electrical instrdment containing a standard, a vibrating index-mirror supported thereby, an independently-supported scale-chamber inclosing said mirror and surrounding said standard, and means-such as screws-for vertically adju 1;- ing said standard in said I chamber, sub antially as described.

10. In an electrical instrument, a base, a circular scale-chamber supported thereon, a central hollow standard resting on said base and passing through said scalechamber, and an index-mirror supported in said standard and inclosed in said scale-chamber, substantially as described.

'11. .In an electrical instrument, a base, a circular scale-chamber supported thereon, a central hollow standard resting on said base and passing through said scale-chamber, an index-mirror supported in said standard and inclosed in said scale-chamber, universal-joint connections between said standard and the top and bottom walls of said chamber, meanssuch as screws-for leveling said base and chamber, and means-such as screws G-for leveling said standard upon said base, substantially as described.

12. In an electrical instrument, a central hollow standard, a vibrating index-mirror supported therein, scale-chamber inclosing said mirror, (through which chamber said standard passes,) and means-such as a tangent-screw and toothed segment-for rotating saidstandard on its axis within'said described.

13. In a galvanometer, a central hollow standard, a vibrating'index-mirror supported therein, an independently-supported chamber having side, top, and bottom walls incloscha-mber, substantially as ing said mirror, (through which chamber said standard passes,) and universal-joint connections between said standard and the top and bottom'plates or walls of said chamber, substantially as described.

14. A galvanometer-coil containing an annular spool or bobbin andtwo encircling conductors located, respectively, upon the periphery and upon one face of said spool, substantially as described. 15. A galvanometer-coil containing an anbobbin having two encircling grooves or channels formed, respectivelyfin its periphery and in one face, and conductors located in saidgrooves, substantially as described.

It. A galvanometer-coil containing an aninclosing.

an independently-supported nular spool or bobbin and 'two conductors forming loops of different diameters, located, respectively, 'upon the periphery and upon one face of said spool, substantially as de- 5 scribed. I

17. In agalvanometer, a coil containing two separate conductors of unequal lengths, but each making the same number of loops or turns, substantially as described.

18. In a galvanometer, a coil containing two separate conductors forming loops, respect- .ively, of diiferent diameters, substantially as described.

19.- In a galvanometer, a coil containing two 5 separate conductors each making the same number of loops or turns, but relatively varying in electrical resistance, substantially as described.

20. In a galvanometer, a coil having its lead- 7 2o ing-out terminals disposed in a line radial to the coil-center and in the horizontal plane of vibration of the magnet-needle, substantially as described.v

21. The combination, with a galvanometer 2 5 containing a vibrating index-mirror and a cen- .tral hollow standard, A, of the collars c and Q, scale-chamber 0, having upper plate, f, and lower plate, I), and the flexible disk 0, inter- 7 I posed between said collarQ and plate 1), sub- 3o stantially as described. 7 v

22. The combination, in a galvanometer, of-

a magnet-needle" and two-rings supported in parallel planes on opposite sides thereof with their centers in line With and equidistant from the center of the n'eedle, and two conductingcoils supported concentrically by each of said ,rings, one conductor being on the face of the ring adjacent to the needle and the other conductor being on the periphery of said ring, the diameters of said coils being relatively such that the circumferences of both coils will lie in the periphery of a cone having its" apex at the needle-center, substantially as described.

23. The combination of thestafidaidAJn-I y dex-mirror H, chamber 0, containing the rim '0', top plate, fiand bottom plate, I), the said plates f and b encircling said standard, respectively, aboveand below the position of the mirror therein, and a scale on the inn er periphbase B, of the base K, scale-chamber C, supported on said base and surrounding said standard-and the centering-plate M on said base K, substantially as described.

EDWARD WESTON. Witnesses:

PARK BENJAMIN, EDGAR GOODWIN. 

